Create RenderTexture version of GetScreenSpaceTemporaryRT

In the places that create a RenderTexture, they need a non-desc dependent function as well.

Plus, use it in the ScalableAO infrastructure.

Author: robbiesri

PostProcessing/Runtime/Effects/ScalableAO.cs

@@ -48,14 +48,11 @@ void DoLazyInitialization(PostProcessRenderContext context)
 
             if (m_Result == null || !m_Result.IsCreated())
             {
-                var tempAORTDesc = context.GetDescriptor(0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Linear);
-
                 // Initial allocation
-                m_Result = new RenderTexture(tempAORTDesc)
-                {
-                    hideFlags = HideFlags.DontSave,
-                    filterMode = FilterMode.Bilinear
-                };
+                m_Result = context.GetScreenSpaceTemporaryRT(0, RenderTextureFormat.ARGB32, RenderTextureReadWrite.Linear);
+                m_Result.hideFlags = HideFlags.DontSave;
+                m_Result.filterMode = FilterMode.Bilinear;
+
                 reset = true;
             }
             else if (m_Result.width != context.width || m_Result.height != context.height) // TODO: convert this to RT width when I implement it

PostProcessing/Runtime/PostProcessRenderContext.cs

@@ -141,16 +141,41 @@ public void GetScreenSpaceTemporaryRT(CommandBuffer cmd, int nameID,
             }
             cmd.GetTemporaryRT(nameID, desc, filter);
 #else
+            int actualWidth = width;
+            int actualHeight = height 
             if (dimScaler > 1)
             {
-                int actualWidth = width / dimScaler;
-                int actualHeight = height / dimScaler;
+                actualWidth /= dimScaler;
+                actualHeight /= dimScaler;
             }
             cmd.GetTemporaryRT(nameID, width, height, depthBufferBits, filter, colorFormat, readWrite);
             // TODO: How to handle MSAA for XR in older versions?  Query cam?      
 #endif
         }
 
+        public RenderTexture GetScreenSpaceTemporaryRT(int depthBufferBits = 0, RenderTextureFormat colorFormat = RenderTextureFormat.Default, 
+                                                        RenderTextureReadWrite readWrite = RenderTextureReadWrite.Default, int dimScaler = 1)
+        {
+#if UNITY_2017_2_OR_NEWER
+            var desc = GetDescriptor(depthBufferBits, colorFormat, readWrite);
+            if (dimScaler > 1)
+            {
+                desc.width /= dimScaler;
+                desc.height /= dimScaler;
+            }
+            return RenderTexture.GetTemporary(desc);
+#else
+            int actualWidth = width;
+            int actualHeight = height 
+            if (dimScaler > 1)
+            {
+                actualWidth /= dimScaler;
+                actualHeight /= dimScaler;
+            }
+            return RenderTexture.GetTemporary(actualWidth, actualHeight, depthBufferBits, colorFormat, readWrite);
+#endif
+        }
+
         // Current active rendering eye (for XR)
         public int xrActiveEye { get; private set; }